Connect to remote unix server using Linux script

[maya_pillai]

Hi all,

1)We need to do a clean up a folder in a remote unix server . What is the best option to connect to remote server? how do we use ssh ? Is there any prerequisite to use ssh?

2) We have to SCP few files to another folder in a remote unix server .

I formed the below command to use in script. Is it of correct usage?

scp -r $POS_HOME/posctl [login nameip address:/home/username/directory]

I have seen public key/private key generation part for SCP. How do we handle this? Does this need to be done as unix admin?


Thanks
Maya

[Roxoff]

scp uses the same keys that ssh uses. Set the keys up for the user the script will run as, you'll want to do this for both the ssh login and the scp file copy.

[RDU]

If you want to cleanup, the scp to the same directory, you could look at rsync. It will work over ssh (with the same keys as before). You just need the rsync package installed (quite standard in many distro) and sshd running.

something like :

$ rsync -av --delete localdir user@server:/destdir

--delete : remove file in destdir wich are no more in localdir (do your cleanup)
-av : a = a set of option like recursive, preserve perm, .... (see man)

An best, rsync transfer only the difference (scp override all files even if they are the same), so you can even sync over internet huge directory (after a first sync).

[maya_pillai]

Thank you Roxoff and RDU!

Here is my script for SCP

scp -r $POSCNTL [login name@ip address:/home/username/directory]
SCP_RETURN=$?
if [[ $SCP_RETURN -eq 0 ]]
then

        echo "Control files copied to landing zone \n | tee -a $logfile
        echo "SCP Return =${SCP_RETURN}

else
        echo "Control files copy error to landing zone .. Exiting\n | tee -a $logfile
        echo "SCP Return =${SCP_RETURN}
        exit $error_exit

fi

The below one is for SSH

ssh loginname@ip address
cd remotehostfolder
rm *

Are these two scripts correct ?

I still have few doubts on key generation part. For the above code to work without asking for a password what all steps I need to take care? (Sorry if it looks so basic..)

Thanks
Maya

[RDU]

second script is wrong. You've to pass the cmd as argument of ssh

e.g.

ssh loginname@remotehost rm -f /path/remotefolder/*

-f (force) or -rf if you want to remove all under that path recursively (be carefull).

DON'T cd then rm. If cd fail, you'll rm on a wrong directory. Do directly "rm pathname/*"

e.g. in your wrong script it will ssh, then when you exit, it will try to change to remotehostfolder wich probably don't exist on your computer, so fail, then rm * all your current directory (probably your script itself and other).

[maya_pillai]

Thank you so much RDU!

Can you pls answer this also?

I still have few doubts on key generation part. For the this code to work without asking for a password what all steps I need to take care?

Maya

[RDU]

e.g. : user1 runing the script on computer client. This script ssh to computer server using user2 :

1.You have to have a set of key on client side (the one who run the script) using the user that will run the script (user1)
[user1@client] $ ssh-keygen -t dsa
It will generate two files in ~/.ssh -> id_dsa and id_dsa.pub (keep the first confidential, it's your private key). The second could be public.

2.You have to add the public key to the server side into the destination user home directory / .ssh / authorized_keys
You can copy / paste or use :
[user1@client] $ ssh-copy-id user2@server

3.Check the right on this file on the server (Important, if right are wrong, ssh will not accept the cnx).
[user2@server] $ chmod 600 ~/.ssh/authorized_keys

4.Now you can connect
[user1@client] $ ssh user2@server uname -a
Linux server .....

[maya_pillai]

Very Clear!! Thank you very much!!

Maya